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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. Opticall follow-ups for the X-ray transient in NGC 2770
  2. X-ray transient in NGC 2770: Optical observations with Astrotel-Caucasus
  3. Optical Spectroscopy of the Transient in NGC 2770
  4. Swift UVOT Observations of the X-ray transient in NGC 2770
  5. Early OT detection of XRF in NGC 2770 in Asiago frames
  6. Bright X-ray transient / possible XRF in NGC 2770: TNG R imaging
  7. Possible XRF in NGC 2770 - NOT observations of the optical counterpart
  8. Bright X-ray Transient (a XRF? ) in NGC 2770 - A SN optical counterpart?
  9. Bright X-ray Transient in NGC 2770 - A low-luminosity XRF?
  10. GRB 071227: Suzaku WAM observation of the prompt emission
  11. GRB 071227: optical afterglow
  12. Further Swift-BAT analysis of GRB 071227
  13. Konus-Wind observation of GRB 071227
  14. GRB 071227: Magellan redshift confirmation
  15. GRB 071227: Swift-XRT refined analysis
  16. GRB 071227: VLT probable redshift of the candidate host galaxy
  17. GRB 071227: Magellan observations
  18. GRB071227: Swift/UVOT refined analysis
  19. GRB 071227: REM NIR and Optical observations
  20. Swift-BAT refined analysis of short GRB 071227
  21. GRB 071227: Swift detection of a burst
  22. GRB071020: optical observations
  23. GRB 070429B: Possible UVOT Detection of an Optical Afterglow
  24. Swift-BAT trigger 298308 is not a GRB
  25. GRB 071208?: Swift detection of a possible burst
  26. IBAS Alert #4772 in not a GRB
  27. GRB 071125: Suzaku WAM observation of the prompt emission
  28. GRB 070429B: Probable host galaxy and redshift
  29. GRB 071129, Swift-BAT refined analysis
  30. GRB 071129: Swift detection of a burst
  31. Konus-Wind and Konus-A observations of GRB 071125
  32. IPN triangulation of very bright GRB 071125
  33. GRB 071112C: Optical/NIR observations
  34. Disregard the "GRB 071126" position
  35. GRB 071126: Enhanced Swift-XRT position
  36. VLA radio detection of GRB 071122
  37. GRB071122: Swift/UVOT Observations
  38. GRB071104: NIR Afterglow Candidate at TNG
  39. GRB 071122: MASTER optical observation
  40. GRB 071122, Swift-BAT refined analysis
  41. GRB 071122 Swift XRT position update sent in error.
  42. GRB 071122 Swift-XRT refined analysis
  43. GRB 071122: Corrected P60 Coordinates
  44. GRB071122: Gemini Absorption redshift
  45. GRB 071122: P60 Optical Afterglow Candidate
  46. GRB 071122: ROTSE-III Optical Limits
  47. GRB 071122: Swift detection of a burst
  48. GRB 071118: P60 Observations
  49. GRB071118 MITSuME OAO optical observation
  50. GRB 071118: Observations from OSN
  51. GRB 071117: VLT observations and probable redshift
  52. Swift/UVOT observations of GRB071118
  53. GRB 071117: Swift-XRT revised position
  54. Konus-Wind and Konus-A observations of GRB 071117
  55. Swift XRT follow-up observations of GRB071008
  56. Swift/UVOT upper limits for GRB 071117
  57. GRB071118: Swift XRT refined analysis
  58. GRB 071117: Gemini Optical Afterglow Discovery
  59. GRB 071118, Swift-BAT refined analysis
  60. GRB 071117: TAROT La Silla observatory optical observations
  61. GRB 071112B: Gemini Image Differencing
  62. GRB 071118: Swift detection of a burst
  63. GRB 071117: Gemini Observations
  64. GRB 071117: Las Campanas optical observations
  65. GRB 071117: Swift-XRT refined analysis
  66. GRB 071117, Swift-BAT refined analysis
  67. VLT FORS2 observations of short hard GRB071112B
  68. GRB 071117: Swift/XRT position
  69. GRB 071117: Initial Swift/UVOT observations
  70. GRB 071117: Swift detection of a bright burst
  71. Swift detection of MXB 0656-072
  72. VLA radio upper limit on GRB 071112C
  73. ATCA radio observations of short hard burst GRB 071112B
  74. GRB 071112C: Optical and NIR data observed with KANATA
  75. Correction to the Swift-BAT Transient Identification (trigger=296683)
  76. GRB 071112C: WSRT Radio Observations
  77. GRB071112C: Errata of MITSuME Ic band photometry
  78. GRB 071112C: optical observation
  79. GRB 071112C: optical observation
  80. GRB 071112C: emission lines and refined VLT redshift
  81. GRB 071112C MITSuME Akeno early optical observation
  82. GRB 071112C: Gemini Absorption Redshift
  83. GRB 071112B: 2nd epoch of Magellan i-band imaging
  84. GRB 071112C: SARA upper limit
  85. GRB 071112C : Second Epoch Lulin R-band observations
  86. GRB071112C MITSuME Okayama Optical Observation
  87. GRB 071112C: Swift-BAT refined analysis
  88. GRB 071112C: Swift/UVOT observations
  89. GRB 071112C: Swift XRT refined analysis
  90. GRB 071112C: Optical observations at Crni Vrh
  91. Swift UVOT upper limits of GRB071112B
  92. GRB 071112C: VLT redshift
  93. GRB 071112B: Magellan i-band imaging
  94. GRB 071112B: Gemini Optical Imaging (Correction)
  95. GRB 071112B: Gemini Optical Imaging
  96. GRB 071112B: Swift-XRT preliminary analysis
  97. GRB 071112B, Swift-BAT partial refined analysis of the SHB
  98. GRB071112C: NOT observations
  99. GRB 071112C: Palomar Pre-Imaging
  100. Swift-BAT trigger 296491 is not a GRB

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